System and method for measuring product flow to an agricultural implement

ABSTRACT

An agricultural implement system is provided including a fluid conduit configured to provide product to a ground engaging tool. The ground engaging tool is configured to deposit the product into soil. The agricultural implement system also includes an air source fluidly coupled to the fluid conduit, and configured to provide an air flow through the fluid conduit in a downstream direction toward the ground engaging tool. The agricultural implement system further includes a product delivery system fluidly coupled to the fluid conduit, and configured to transfer the product into the air flow. In addition, the agricultural implement system includes a product flow measurement system configured to determine a mass flow rate of the product based on a pressure drop between an upstream portion of the fluid conduit and a downstream portion of the fluid conduit, a flow rate of the air flow, and a velocity of the air flow.

BACKGROUND

The invention relates generally to a system and method for measuringproduct flow to an agricultural implement.

Generally, seeding implements are towed behind a tractor or other workvehicle via a hitch assembly secured to a rigid frame of a planter orseeder. These seeding implements typically include one or more groundengaging tools or openers that form a seeding path for seed depositioninto the soil. The openers are used to break the soil to enable seeddeposition. After the seeds are deposited, each opener is followed by apacker wheel that packs the soil on top of the deposited seeds.

In certain configurations, an air cart is used to meter and deliverproduct (e.g., seed, fertilizer, etc.) to ground engaging tools withinthe seeding implement. Certain air carts include a metering systemconfigured to deliver metered quantities of product into an airflow thattransfers the product to the openers. To ensure that a desired quantityof product is delivered, a calibration procedure may be performed tocalibrate rotation of meter rollers within the metering system to a massflow rate of product to the openers. Some calibration procedures involveuser intervention throughout the process. For example, a user may attacha bag to the metering system to collect expelled product. The user maythen instruct the metering system to rotate the meter rollers through adesired number of rotations (e.g., 50 100, 150, 200, etc.). Next, theuser may weigh the collected product and enter the weight into a userinterface. A controller may then automatically compute a calibrationthat associates product mass flow rate with rotation of the meterrollers. Such user intervention may be time consuming, and may result ininaccurate calibrations, thereby causing too much or too little productto be delivered.

BRIEF DESCRIPTION

In one embodiment, an agricultural implement system includes a fluidconduit configured to provide product to a ground engaging tool. Theground engaging tool is configured to deposit the product into soil. Theagricultural implement system also includes an air source fluidlycoupled to the fluid conduit, and configured to provide an air flowthrough the fluid conduit in a downstream direction toward the groundengaging tool. The agricultural implement system further includes aproduct delivery system fluidly coupled to the fluid conduit, andconfigured to transfer the product into the air flow. In addition, theagricultural implement system includes a product flow measurement systemconfigured to determine a mass flow rate of the product based on apressure drop between an upstream portion of the fluid conduit and adownstream portion of the fluid conduit, a flow rate of the air flow,and a velocity of the air flow.

In another embodiment, a system for measuring product flow to anagricultural implement includes a first pressure sensor configured tooutput a first signal indicative of fluid pressure within an upstreamportion of a fluid conduit. The fluid conduit is configured to conveyproduct to the agricultural implement via an air flow in a downstreamdirection. The system also includes a second pressure sensor configuredto output a second signal indicative of fluid pressure within adownstream portion of the fluid conduit. The system further includes anair flow sensor configured to output a third signal indicative of a flowrate of the air flow, and a fourth signal indicative of a velocity ofthe air flow. In addition, the system includes a controllercommunicatively coupled to the first pressure sensor, to the secondpressure sensor, and to the air flow sensor. The controller isconfigured to determine a pressure drop between the upstream anddownstream portions of the fluid conduit based on the first signal andthe second signal. The controller is also configured to determine a massflow rate of the product based on the pressure drop, the third signaland the fourth signal.

In a further embodiment, a method for measuring product flow to anagricultural implement includes measuring a pressure drop between anupstream portion of a fluid conduit and a downstream portion of thefluid conduit. The fluid conduit is configured to convey product to theagricultural implement via an air flow in a downstream direction. Themethod also includes measuring a flow rate of the air flow, andmeasuring a velocity of the air flow. In addition, the method includesdetermining a mass flow rate of the product based on the pressure drop,the flow rate of the air flow, and the velocity of the air flow.

DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a side view of an exemplary air cart that may employ anembodiment of a product flow measurement system;

FIG. 2 is a schematic diagram of an exemplary product delivery systemthat may be used within the air cart of FIG. 1;

FIG. 3 is a schematic diagram of an embodiment of a product flowmeasurement system that may be used within the air cart of FIG. 1;

FIG. 4 is an exemplary graph of mass flow ratio versus pressure drop;

FIG. 5 is a flowchart of an exemplary method for measuring andcontrolling product flow to an agricultural implement; and

FIG. 6 is a flowchart of an exemplary method for determining a mass flowrate of product through a fluid conduit.

DETAILED DESCRIPTION

FIG. 1 is a side view of an air cart that may employ an embodiment of aproduct flow measurement system. In the illustrated embodiment, animplement 10 is coupled to an air cart 12, which is towed behind theimplement 10 during operation and transport. The implement 10 includes atool frame 14, and a ground engaging tool 16 coupled to the tool frame14. The ground engaging tool 16 is configured to excavate a trench intothe soil 18 to facilitate seed and/or fertilizer deposition. In theillustrated embodiment, the ground engaging tool 16 receives product(e.g., seed, fertilizer, etc.) from a product distribution header 20 viaa hose 22 extending between the header 20 and the ground engaging tool16. Although only one ground engaging tool 16, product distributionheader 20, and hose 22 are employed within the illustrated embodiment,it should be appreciated that the implement 10 may include additionaltools 16, headers 20 and/or hoses 22 in alternative embodiments tofacilitate product delivery across a wide swath of soil 18. In addition,the implement 10 includes wheel assemblies 24 which contact the soilsurface 18 and enable the implement 10 to be pulled by a tow vehicle.

While the air cart 12 is towed behind the implement 10 in theillustrated embodiment, it should be appreciated that the air cart 12may be towed directly behind a tow vehicle in alternative embodiments.For example, the air cart may be coupled to the tow vehicle by a hitchassembly, and the implement 10 may be towed behind the air cart 12. Infurther embodiments, the implement 10 and the air cart 12 may be part ofa single unit that is towed behind a tow vehicle, or elements of aself-propelled vehicle configured to distribute product across a field.

In the illustrated embodiment, the air cart 12 includes a storage tank26, a frame 28, wheels 30, a metering system 32, and an air source 34.The frame 28 includes a towing hitch configured to couple to theimplement 10 or tow vehicle, thereby enabling the air cart 12 to betowed across a field. In certain configurations, the storage tank 26includes multiple compartments for storing various flowable particulatematerials. For example, one compartment may include seeds, and anothercompartment may include a dry/granular fertilizer. In suchconfigurations, the air cart 12 may be configured to deliver both seedand fertilizer to the implement 10 via separate distribution systems, oras a mixture through a single distribution system.

The seed and/or fertilizer within the storage tank 26 are gravity fedinto the metering system 32, thereby enabling the metering system todistribute a desired quantity of product to the ground engaging tools 16of the implement 10. In the present embodiment, the metering system 32includes sectioned meter rollers to regulate the flow of product fromthe storage tank 26 into an air flow provided by the air source 34. Theair flow then carries the product through a hose 36 to the implement 10,thereby supplying the ground engagement tools 16 with seed and/orfertilizer for deposition into the soil. Although only one hose 36 isincluded in the illustrated embodiment, additional hoses may be may beemployed in alternative embodiments to transfer product from the aircart 12 to various distribution headers 20 of the implement 10.

As discussed in detail below, the air cart 12 may include a system formeasuring product flow to the agricultural implement 10. In certainembodiments, the product flow measurement system includes a firstpressure sensor configured to output a first signal indicative of fluidpressure within an upstream portion of a fluid conduit, and a secondpressure sensor configured to output a second signal indicative of fluidpressure within a downstream portion of the fluid conduit. The fluidconduit is configured to convey product to the agricultural implementvia an air flow in a downstream direction. The product flow measurementsystem also includes an air flow sensor configured to output a thirdsignal indicative of a flow rate of the air flow, and a fourth signalindicative of a velocity of the air flow. A controller, communicativelycoupled to the first pressure sensor, to the second pressure sensor, andto the air flow sensor, is configured to determine a pressure dropbetween the upstream and downstream portions of the fluid conduit basedon the first signal and the second signal. The controller is alsoconfigured to determine a mass flow rate of product through the fluidconduit based on the pressure drop, the third signal and the fourthsignal. In certain embodiments, the controller is configured to computethe mass flow rate of the product based on the pressure drop, the thirdsignal, the fourth signal, and at least one empirical parameterassociated with the product.

Because the mass flow rate of product to the agricultural implement 10is determined based on measured parameters, the process of manuallycalibrating the metering system prior to operation is obviated. Forexample, to manually calibrate a metering system, a user may attach abag to the metering system to collect expelled product. The user maythen instruct the metering system to rotate the meter rollers through adesired number of rotations (e.g., 50 100, 150, 200, etc.). Next, theuser may weigh the collected product and enter the weight into a userinterface. A controller may then automatically compute a calibrationthat associates product mass flow rate with rotation of the meterrollers. Such user intervention may be time consuming, and may result ininaccurate calibrations, thereby causing too much or too little productto be delivered. In contrast, the product flow measurement systemdescribed below is configured to automatically determine the productmass flow rate during operation of the implement, thereby obviating thecalibration procedure. In addition, because the product flow measurementsystem is configured to determine the product mass flow rate viameasured parameters, product (e.g., seed, fertilizer, etc.) within theair cart 12 may be interchanged without recalibrating the meteringsystem.

In certain embodiments, the controller is configured to adjust productflow to the agricultural implement based on the determined product massflow rate. For example, the controller may be configured to instruct themetering system to control a rotation rate of the meter rollers toadjust the product flow. By way of example, an operator may input adesired product flow rate into a user interface. The controller may thendetermine the actual mass flow rate of product to the implement based onthe measured parameters. Next, the controller may increase or decreasethe rotation rate of the meter rollers to provide the desired productmass flow rate to the implement. In further embodiments, the controllermay be configured to instruct the air source to adjust the air flowbased on the determined mass flow rate of product, the measured massflow rate of the air flow, and/or the measured velocity of the air flow.For example, the controller may be configured to instruct the air sourceto increase the air flow if the measured air flow velocity is less thana lower threshold value, and to decrease the air flow if the measuredair flow velocity is greater than an upper threshold value. In thismanner, sufficient air flow may be provided to substantially reduce thepossibility of blockage formation within the product distribution hoses.In addition, the air flow may be limited to substantially reduce thepossibility of product being blown out of a seeding trench.

FIG. 2 is a schematic view of a product delivery system, such as theillustrated metering system 32, that may be used within the air cart ofFIG. 1. As illustrated, the air source 34 is coupled to a conduit 38extending to the hose 36, and configured to flow air 40 past themetering system 32. The air source 34 may be a pump or blower powered byan electric or hydraulic motor, for example. Flowable particulateproduct 42 (e.g., seed, fertilizer, etc.) within the storage tank 26flows by gravity into the metering system 32. The metering system 32includes one or more meter rollers 44 configured to regulate the flow ofproduct 42 into the air flow 40. More particularly, the metering system32 may include multiple meter rollers 44 disposed adjacent to oneanother along a longitudinal axis of the rollers 44. For example,certain metering systems 32 include seven meter rollers 44. Such systems32 are known as “7-run” metering assemblies. However, alternativeembodiments may include more or fewer meter rollers 44, e.g., 5, 6, 7,8, 9, or more. Further embodiments may include one continuous meterroller 44.

Each meter roller 44 includes an interior cavity 46 configured toreceive a shaft that drives the meter roller 44. In the presentembodiment, the cavity 46 has a hexagonal cross section. However,alternative embodiments may include various other cavity configurations(e.g., triangular, square, keyed, splined, etc.). The shaft is coupledto a drive unit, such as an electric or hydraulic motor, configured torotate the meter rollers 44. Alternatively, the meter rollers 44 may becoupled to a wheel 30 by a gear assembly such that rotation of the wheel30 drives the meter rollers 44 to rotate. Such a configuration willautomatically vary the rotation rate of the meter rollers 44 based onthe speed of the air cart 12.

Each meter roller 44 also includes multiple flutes 48 and recesses 50.The number and geometry of the flutes 48 are particularly configured toaccommodate the product 42 being distributed. The illustrated embodimentincludes six flutes 48 and a corresponding number of recesses 50.Alternative embodiments may include more or fewer flutes 48 and/orrecesses 50. For example, the meter roller 44 may include 1, 2, 3, 4, 5,6, 7, 8, 9, 10, or more flutes 48 and/or recesses 50. In addition, thedepth of the recesses 50 and/or the height of the flutes 48 areconfigured to accommodate the product 42 within the storage tank 26. Forexample, a meter roller 44 having deeper recesses 50 and fewer flutes 48may be employed for larger seeds, while a meter roller 44 havingshallower recesses 50 and more flutes 48 may be employed for smallerseeds. Other parameters such as flute pitch (i.e., rotation relative toa longitudinal axis) and flute angle (i.e., rotation relative to aradial axis) may also be varied in alternative embodiments.

For a particular meter roller configuration, the rotation rate of themeter roller 44 controls the flow of product 42 into the air stream 40.Specifically, as the meter roller 44 rotates, product is transferredthrough an opening 52 in the metering system 32 into the conduit 38. Theproduct then mixes with air from the air source 34, thereby forming anair/product mixture 54. The mixture then flows to the ground engagingtools 16 of the implement 10 via the hose 36, where the seeds and/orfertilizer are deposited within the soil. While the illustratedembodiment utilizes a meter roller 44 to supply product to the airstream 40, it should be appreciated that alternative embodiments mayemploy other devices, such as an auger, to regulate the flow of productto the conduit 38.

As discussed in detail below, the air cart 12 may include a product flowrate measurement system configured to determine a mass flow rate of theproduct into the air stream. For example, in certain embodiments, theproduct flow rate measurement system includes a controller configured todetermine a mass flow rate of product through the fluid conduit 38 basedon a pressure drop between an upstream portion and a downstream portionof the fluid conduit, a mass flow rate of the air flow, and a velocityof the air flow. Because the mass flow rate of product to theagricultural implement 10 is determined based on measured parameters,the process of manually calibrating the metering system prior tooperation is obviated. In addition, the controller may be configured toadjust the product flow to the agricultural implement based on thedetermined product mass flow rate. In such configurations, a measuredquantity of product may be supplied to the implement, therebyestablishing a desired distribution of product across the field.

FIG. 3 is a schematic diagram of an embodiment of a product flowmeasurement system that may be used within the air cart of FIG. 1. Aspreviously discussed, the air source 34 is configured to provide an airflow 40 into the fluid conduit 38. In addition, the metering system 32is configured to deliver product into the air flow 40, therebyestablishing a product/air mixture that flows in a downstream direction56 toward the implement 10. In the illustrated embodiment, air cart 12includes a product flow measurement system configured to determine amass flow rate of product through the fluid conduit 38. As illustrated,the product flow measurement system includes a first pressure sensor 58configured to measure fluid pressure within an upstream portion 60 ofthe fluid conduit, and a second pressure sensor 62 configured to measurefluid pressure within a downstream portion 64 of the fluid conduit 38.The first pressure sensor 58 is fluidly coupled to the conduit 38 via afirst pressure tap 66, and the second pressure sensor 62 is fluidlycoupled to the conduit 38 via a second pressure tap 68. The sensors 58and 62 are configured to measure the fluid pressure within the conduit38 via the respective pressure taps, and to output respective signalsindicative of the measured pressure. As will be appreciated, the firstand sensor pressure sensors may include fiber optic sensors, mechanicaldeflection sensors, piezoelectric sensors, microelectromechanical system(MEMS) sensors, or any other suitable sensor configured to output asignal indicative of fluid pressure within the conduit 38.

The product flow measurement system also includes an air flow sensor 70positioned upstream (i.e., along an upstream direction 72) of meteringsystem 32. The air flow sensor 70 is configured to measure a flow rateof the air flow 40, and a velocity of the air flow 40. In certainembodiments, the air flow sensor 70 includes an orifice plate having anaperture with a smaller diameter than the fluid conduit 38. As the airflow 40 passes through the aperture, the fluid pressure decreases andthe velocity increases. By measuring the pressure difference between theair flow upstream and downstream of the aperture, the flow rate (e.g.,volumetric flow rate, mass flow rate, etc.) of air flow 40 may bedetermined. In further embodiments, the air flow sensor 70 includes ahot wire sensor having an electrically heated element extending throughthe air flow. As will be appreciated, heat transfer from the wire to theair flow is at least partially dependent on the flow rate of the airflow across the wire. Therefore, by measuring the electrical currentsufficient to heat the wire to a desired temperature, the flow rate ofair flow 40 may be determined. In addition, the air flow sensor 70 mayinclude a pitot tube configured to measure both static and dynamicpressures within the fluid conduit 38. By comparing the static anddynamic pressures, the flow rate of the air flow 40 may be determined.As will be appreciated, if a volumetric flow rate is measured, the massflow rate may be calculated based on the density of the air.Furthermore, it should be appreciated that the orifice plate, the hotwire sensor and the pitot tube may be employed to measure the velocityof the air flow 40. It should also be appreciated that alternativeembodiments may include other suitable air flow sensors configured tomeasure flow rate and/or velocity of the air flow 40.

In the illustrated embodiment, the first pressure sensor 58, the secondpressure sensor 62 and the air flow sensor 70 are communicativelycoupled to a controller 74. The controller 74 is configured to receive afirst signal from the first pressure sensor 58 indicative of fluidpressure within the upstream portion 60 of the fluid conduit 38, and toreceive a second signal from the second pressure sensor 62 indicative offluid pressure within the downstream portion 64 of the fluid conduit 38.The controller 74 is also configured to receive a third signal from theair flow sensor 70 indicative of a flow rate of air flow 40, and afourth signal from the air flow sensor 70 indicative of a velocity ofthe air flow. Alternatively, the controller 74 may be configured toreceive the third signal or the fourth signal, and to determine both themass flow rate of the air flow and the velocity of the air flow based onthe single signal. Once the signals have been received, the controller74 may determine a pressure drop between the upstream and downstreamportions of the conduit 38 based on the first and second signals. Thecontroller 74 may then determine a mass flow rate of product through thefluid conduit based on the pressure drop, the mass flow rate of the airflow and the velocity of the air flow. Because the mass flow rate ofproduct to the agricultural implement 10 is determined based on measuredparameters, the time associated with performing a manual calibrationprocess prior to operation of the implement may be substantially reducedor eliminated.

While the illustrated embodiment includes separate pressure sensors 58and 62, it should be appreciated that alternative embodiments mayinclude a single pressure sensor configured to directly measure thepressure drop between the upstream and downstream portions of the fluidconduit 38. For example, in certain embodiments, a differential pressuresensor may be fluidly coupled to the first pressure tap 66, and to thesecond pressure tap 68. In such embodiments, the differential pressuresensor may be configured to output a signal indicative of the pressuredifference (i.e., pressure drop) between the upstream portion 60 of thefluid conduit 38 and the downstream portion 64 of the fluid conduit 38.Accordingly, the controller 74 may determine the product mass flow ratebased on the differential pressure signal.

In certain embodiments, the controller 74 may be configured to establisha relationship between the measured parameters (i.e., flow rate of theair flow, velocity of the air flow, and pressure drop through the fluidconduit) and the mass flow rate of product through the fluid conduitbased on empirically derived parameters. For example, at least oneempirical parameter may be associated with each product (e.g., seed,fertilizer, etc.), and the controller 74 may be configured to determinethe mass flow rate of product through the fluid conduit 38 based on thepressure drop, the mass flow rate of the air flow, the velocity of theair flow, and the empirical parameters. The empirical parameters may bestored in an empirical parameter database 76, which includes a list ofproducts and a corresponding list of empirical parameters. By way ofexample, prior to operation of the implement 10, an operator may selectthe type of product (e.g., seed, fertilizer, etc.) stored within thetank 26 of the air cart 12 via a user interface 78. The controller 74,in turn, may select the appropriate empirical parameters from thedatabase 76 based on the selected product. During operation of theimplement, the controller 74 may determine the mass flow rate of productto the implement 10 based on the pressure drop, the flow rate of the airflow, the velocity of the air flow, and the empirical parametersassociated with the product flowing to the ground engaging tools 16.

In certain embodiments, the controller 74 is configured to determine theproduct mass flow rate based on a table of values associated with aparticular product. For example, once the appropriate empiricalparameters are selected, the controller may establish a table thatprovides a relationship between the measured pressure drop, the flowrate of the air flow, the velocity of the air flow, and the mass flowrate of product to the implement 10. Once the table is established, thecontroller 74 may determine the mass flow rate of product based on themeasured parameters during operation of the implement 10.

In further embodiments, the controller 74 is configured to determine themass flow rate of product based on a computation involving pressuredrop, mass flow rate of the air flow, velocity of the air flow, and theempirical parameters. For example, in certain embodiments, product massflow rate may be determined by the following equation:

m _(p) =m _(a)·[(a ₁ e ^(a) ² ^(v))Δp−ln(b ₁ v ³ +b ₂ v ² +b ₃ v+b ₄)]

where m_(p) is the mass flow rate of product through the fluid conduit,m_(a) is the mass flow rate of the air flow, Δp is the pressure dropthrough the conduit, v is the velocity of the air flow, and a₁, a₂, b₁,b₂, b₃ and b₄ are empirical parameters. In such embodiments, thecontroller 74 may compute the mass flow rate of product through theconduit based on the selected empirical parameters and the measuredvalues. While the equation presented above provides an accuratedetermination of product mass flow rate through certain agriculturalsystems, it should be appreciated that alternative systems may utilizeother equations to compute product mass flow rate based on the pressuredrop, the mass flow rate of the air flow, the velocity of the air flow,and certain empirical parameters.

As discussed in detail below, the parameters a₁, a₂, b₁, b₂, b₃ and b₄may be empirically determined by correlating a measured pressure drop, amass flow rate of the air flow and a velocity of the air flow withparticular product mass flow rates. Alternatively, the parameters may bedetermined based on physical properties of the product. For example, theparameters may be computed via a mathematical model that utilizes themass of each product particle, the shape of each product particle, thesurface friction of each product particle and/or other physicalproperties to determine the parameters.

In addition, while the product flow measurement system described aboveis configured to determine the product mass flow rate based on themeasured pressure drop, the mass flow rate of the air flow, and thevelocity of the air flow, it should be appreciated that alternativeproduct flow measurement systems may be configured to receive additionalparameters to facilitate determination of the product mass flow rate.For example, the product flow measurement system may include additionalsensors configured to measure a temperature of the air flow, a pressureof the air flow and/or a relative humidity of the air flow, among otherparameters. In such a configuration, the controller 74 may be configuredto determine the product mass flow rate based on the measured pressuredrop, the mass flow rate of the air flow, the velocity of the air flow,and the additional measured parameters.

In certain embodiments, the controller 74 is configured to adjustproduct flow to the agricultural implement based on the determined massflow rate of product. For example, in the illustrated embodiment, thecontroller 74 is communicatively coupled to the metering system 32, andconfigured to instruct the metering system to adjust product flow to theconduit 38 based on the determined mass flow rate of product. By way ofexample, if the controller 74 determines that the mass flow rate ofproduct is lower than desired, the controller 74 may instruct themetering system 32 to increase the meter roller rotation rate toincrease product flow into the air stream 40. Conversely, if thecontroller 74 determines that the mass flow rate of product is higherthan desired, the controller 74 may instruct the metering system 32 todecrease the meter roller rotation rate to decrease product flow intothe air stream 40. In this manner, controller 74 may maintain a desiredflow rate of product to the ground engaging tools 16 of the implement10.

Furthermore, in the illustrated embodiment, the controller 74 iscommunicatively coupled to the air source 34, and configured to instructthe air source to adjust the air flow based on the determined mass flowrate of product, the measured flow rate of the air flow and/or themeasured velocity of the air flow. For example, the controller 74 may beconfigured to establish a suitable range of air flows (e.g., between alower threshold value and an upper threshold value) based on thedetermined mass flow rate of product. By way of example, the controller74 may establish a lower range of air flows while less product isflowing through the conduit 38, and a higher range of air flows whilemore product is flowing through the conduit 38. In this manner, the airflow may be particularly selected to facilitate product flow from themetering system 32 to the implement 10. Once the desired range of airflows is established, the controller 74 may instruct the air source 34to increase the air flow if the measured air flow velocity is less thanthe lower threshold value, and to decrease the air flow if the measuredair flow velocity is greater than the upper threshold value. As aresult, sufficient air flow may be provided to substantially reduce thepossibility of blockage formation within the product distribution hoses.In addition, the air flow may be limited to substantially reduce thepossibility of product being blown out of a seeding trench.

By way of example, prior to operation, an operator may input a producttype into the user interface 78. For example, the operator may selectbetween a variety of seeds (e.g., canola, wheat, chickpea, etc.) and/orfertilizers. The controller 74 may then select the appropriate empiricalparameters from the empirical parameter database 76 based on the productselection. Next, the controller 74 may establish a relationship betweenthe mass flow rate of product and the measured pressure drop, the flowrate of the air flow, and the velocity of the air flow based on theselected empirical parameters. The operator may then enter a desiredproduct coverage density (e.g., in terms of mass per acre) into the userinterface 78.

In certain embodiments, the desired product coverage density may beautomatically selected based on implement position. For example, in theillustrated embodiment, a spatial locating device 80 (e.g., globalpositioning system (GPS) receiver) is communicatively coupled to thecontroller 74, and configured to output a signal indicative ofimplement/air cart position. As will be appreciated, the spatiallocating device 80 may be coupled to the implement 10, to the air cart12, or to any other suitable location (e.g., tow vehicle, etc.). Byadjusting the target product coverage density based on implementposition, product may be applied to the field more efficiently than aneven product distribution.

Once the product coverage density is selected, the controller 74 maydetermine a target product mass flow rate based on the speed of theimplement 10. For example, if the desired coverage density is onekilogram per acre, and the implement traverses one acre in 10 seconds,the controller 74 will establish a target mass flow rate about 0.1 kg/s.As will be appreciated, the speed of the implement may be measured by aspeedometer on the implement 10, the air cart 12, or the tow vehicle.Alternatively, the ground speed may be measured by the spatial locatingdevice 80.

The controller 74 may then measure the mass flow rate of product to theimplement 10 based on the pressure drop, the mass flow rate of the airflow, the velocity of the air flow, and the selected empiricalparameters. If the determined mass flow rate of product is higher thanthe target value, the controller 74 will instruct the metering system 32to reduce the rotation rate of the meter rollers. Conversely, if thedetermined mass flow rate of product is lower than the target value, thecontroller 74 will instruct the metering system 32 to increase therotation rate of the meter rollers. The controller 74 will alsodetermine the desired air flow range based on the measured mass flowrate of product, and adjust the blower speed such that the resultant airflow is within the desired range. Consequently, the implement willprovide a desired quantity of product to the field, while obviating thetime consuming calibration procedure.

While the product flow measurement system is described above withreference to an air cart 12, it should be appreciated that the productflow measurement system may be employed within any suitable agriculturalsystem configured to convey product to a ground engaging tool via an airflow. For example, in certain embodiments, the product flow measurementsystem may be utilized within a self-contained vehicle having a productdistribution system and ground engaging tools configured to receiveproduct from the product distribution system via an air flow. It shouldalso be appreciated that the product flow measurement system may bedistributed between an air cart 12 and an implement 10. For example, incertain embodiments, the air flow sensor 70 may be coupled to the aircart 12, and the first and second pressure sensors 58 and 62 may becoupled to the implement 10. In such embodiments, the implement mayinclude multiple sets of pressure sensors to measure the pressure dropto each ground engaging tool, or group of ground engaging tools. Themass flow rate to each tool, or group of tools, may then be determinedbased on the respective pressure drop.

FIG. 4 is an exemplary graph 82 of mass flow ratio versus pressure drop.As illustrated, a horizontal axis 84 represents pressure drop, avertical axis 86 represents mass flow ratio, and a first curve 88represents an exemplary relationship between mass flow ratio andpressure drop at a first air flow velocity. In the illustratedembodiment, the mass flow ratio is the ratio of the product mass flowrate to the mass flow rate of the air flow. As illustrated by the firstcurve 88, the mass flow ratio increases as the pressure drop increases.Consequently, a relationship may be established between mass flow ratioand pressure drop for a particular air flow velocity. For example, inthe illustrated embodiment, the first curve 88 is substantially linear,and has a first slope 90. Based on this curve, if the velocity of theair flow into the fluid conduit and the pressure drop are measured, themass flow ratio may be determined. The mass flow rate of product maythen be determined based on the mass flow ratio and the mass flow rateof the air flow.

The graph 82 also includes a second curve 92 having a second slope 94,and a third curve 96 having a third slope 98. The second curve 92represents the relationship between mass flow ratio and pressure dropfor a second air flow velocity, and the third curve 96 represents therelation between mass flow ratio and pressure drop for a third velocity.In the illustrated embodiment, the second velocity is greater than thefirst velocity, and the third velocity is greater than the secondvelocity. Accordingly, for a particular mass flow ratio, pressure dropincreases as air flow velocity increases. In addition, the slope of thecurves decreases as velocity increases. Based on this series of curves,a two-dimensional relationship between mass flow ratio, pressure dropand air flow velocity may be established.

By way of example, to generate the series of curves, a product (e.g.,seed, fertilizer, etc.) may be loaded into the tank 26 of an exemplaryair cart 12. The metering system 32 may then be calibrated to establisha relationship between meter roller rotation and product mass flow rate.The air flow velocity and the product mass flow rate may beindependently varied (e.g., via varying blower speed and varying meterroller rotation rate), and the pressure drop, the air flow velocity andthe mass flow rate of the air flow may be measured. Once therelationship between the pressure drop, the mass flow rate of the airflow, the velocity of the air flow, and the mass flow rate of product isestablished, a table may be generated that enables the controller 74 todetermine product mass flow rate during operation of the implement basedon the measured parameters. Alternatively, empirical parameters may begenerated to facilitate computation of the product mass flow rate basedon an empirical equation, such as the equation described above.

As will be appreciated, the series of curves may vary (e.g., slope,y-intercept, etc.) based on product. Therefore, a table and/or a seriesof empirical parameters may be generated for each product that may bedistributed by the air cart 12. These tables and/or empirical parametersmay be stored in a database, thereby enabling an operator to select theappropriate table/empirical parameters for a particular product.Furthermore, while linear curves are shown in the illustrated graph 82,it should be appreciated that alternative relationships between massflow ratio and pressure drop may be defined in alternative embodiments.In addition, it should be appreciated that the relationship between massflow ratio and pressure drop may vary based on physical parameters ofthe air cart 12/implement 10. For example, elevations changes, bendswithin the conduit 38 and/or variations in surface roughness may affectthe measured pressure drop. Consequently, a series of curves may begenerated for each air cart configuration, thereby enhancing theaccuracy of product mass flow rate determination.

FIG. 5 is a flowchart of an exemplary method 100 for measuring andcontrolling product flow to an agricultural implement. First, asrepresented by block 102, fluid pressure within an upstream portion ofthe fluid conduit 38 is measured. Next, fluid pressure within adownstream portion of the fluid conduit 38 is measured, as representedby block 104. For example, the fluid pressure may be measured bypressure sensors fluidly coupled to the conduit 38. A pressure dropbetween the upstream portion and the downstream portion of the fluidconduit is then determined, as represented by block 106. For example,the controller 74 may compare signals output from the pressure sensorsto determine the pressure drop along the conduit 38. Next, asrepresented by block 108, a flow rate of the air flow is measured, and avelocity of the air flow is measured, as represented by block 110. Incertain embodiments, an air flow sensor, positioned upstream of themetering system, may be configured to measure the flow rate and velocityof the air flow, and to output signals indicative of the measuredparameters to the controller 74. A mass flow rate of product through thefluid conduit is then determined based on the pressure drop, the massflow rate of the air flow, and the velocity of the air flow, asrepresented by block 112.

Product flow to the implement is adjusted based on the determined massflow rate of product, as represented by block 114. For example, if thecontroller 74 determines that the mass flow rate of product is lowerthan desired, the controller 74 may instruct the metering system 32 toincrease the meter roller rotation rate to increase product flow intothe air stream 40. Conversely, if the controller 74 determines that themass flow rate of product is higher than desired, the controller 74 mayinstruct the metering system 32 to decrease the meter roller rotationrate to decrease product flow into the air stream 40. Finally, asrepresented by block 116, the air flow into the fluid conduit 38 isadjusted based on the determined mass flow rate of product.Consequently, a sufficient air flow may be provided to substantiallyreduce the possibility of blockage formation within the productdistribution hoses. In addition, the air flow may be limited tosubstantially reduce the possibility of product being blown out of aseeding trench.

FIG. 6 is a flowchart of an exemplary method 112 for determining a massflow rate of product through a fluid conduit. First, as represented byblock 118, an empirical parameter is selected from a list of empiricalparameters based on the type product. The mass flow rate of product isthen determined based on the selected empirical parameter, asrepresented by block 120. For example, the controller 74 may beconfigured to determine the mass flow rate of product flowing throughthe conduit 38 based on a table of values associated with a particularproduct. Alternatively, the controller 74 may be configured to determinethe mass flow rate of product based on a computation involving pressuredrop, flow rate of the air flow, velocity of the air flow, and theempirical parameters. Because the mass flow rate of product to theagricultural implement 10 is determined based on measured parameters,the process of manually calibrating the metering system prior tooperation is obviated.

While only certain features of the invention have been illustrated anddescribed herein, many modifications and changes will occur to thoseskilled in the art. It is, therefore, to be understood that the appendedclaims are intended to cover all such modifications and changes as fallwithin the true spirit of the invention.

1. An agricultural implement system, comprising: a fluid conduitconfigured to provide product to a ground engaging tool, wherein theground engaging tool is configured to deposit the product into soil; anair source fluidly coupled to the fluid conduit, and configured toprovide an air flow through the fluid conduit in a downstream directiontoward the ground engaging tool; a product delivery system fluidlycoupled to the fluid conduit, and configured to transfer the productinto the air flow; and a product flow measurement system configured todetermine a mass flow rate of the product based on a pressure dropbetween an upstream portion of the fluid conduit and a downstreamportion of the fluid conduit, a flow rate of the air flow, and avelocity of the air flow.
 2. The system of claim 1, wherein the productflow measurement system is configured to determine the mass flow rate ofthe product based on the pressure drop, the flow rate of the air flow,the velocity of the air flow, and at least one empirical parameterassociated with the product.
 3. The system of claim 2, wherein the massflow rate of the product is determined according to the equation:m _(p) =m _(a)·[(a ₁ e ^(a) ² ^(v))Δp−ln(b ₁ v ³ +b ₂ v ² +b ₃ v+b ₄)],where m_(p) is the mass flow rate of the product, m_(a) is a mass flowrate based on the flow rate of the air flow, Δp is the pressure drop, vis the velocity of the air flow, and a₁, a₂, b₁, b₂, b₃ and b₄ areempirical parameters.
 4. The system of claim 2, wherein the product flowmeasurement system is configured to select the at least one empiricalparameter from a list of empirical parameters based on a selectedproduct.
 5. The system of claim 1, wherein the product comprises seed,granular fertilizer, or a combination thereof.
 6. A system for measuringproduct flow to an agricultural implement, comprising: a first pressuresensor configured to output a first signal indicative of fluid pressurewithin an upstream portion of a fluid conduit, wherein the fluid conduitis configured to convey product to the agricultural implement via an airflow in a downstream direction; a second pressure sensor configured tooutput a second signal indicative of fluid pressure within a downstreamportion of the fluid conduit; an air flow sensor configured to output athird signal indicative of a flow rate of the air flow, and a fourthsignal indicative of a velocity of the air flow; and a controllercommunicatively coupled to the first pressure sensor, to the secondpressure sensor, and to the air flow sensor, wherein the controller isconfigured to determine a pressure drop between the upstream anddownstream portions of the fluid conduit based on the first signal andthe second signal, and the controller is configured to determine a massflow rate of the product based on the pressure drop, the third signaland the fourth signal.
 7. The system of claim 6, wherein the controlleris configured to determine the mass flow rate of the product based onthe pressure drop, the third signal, the fourth signal, and at least oneempirical parameter associated with the product.
 8. The system of claim7, wherein the mass flow rate of the product is determined according tothe equation:m _(p) =m _(a)·[(a ₁ e ^(a) ² ^(v))Δp−ln(b ₁ v ³ +b ₂ v ² +b ₃ v+b ₄)],where m_(p) is the mass flow rate of the product, m_(a) is a mass flowrate based on the flow rate of the air flow, Δp is the pressure drop, vis the velocity of the air flow, and a₁, a₂, b₁, b₂, b₃ and b₄ areempirical parameters.
 9. The system of claim 7, wherein the controlleris configured to select the at least one empirical parameter from a listof empirical parameters based on a fifth signal indicative of a selectedproduct.
 10. The system of claim 9, comprising a user interfacecommunicatively coupled to the controller, and configured to output thefifth signal based on user input.
 11. The system of claim 6, wherein theair flow sensor is positioned upstream of a region in which the productis supplied to the fluid conduit.
 12. The system of claim 6, wherein thefirst pressure sensor, the second pressure sensor, or a combinationthereof, is configured to fluidly couple to the fluid conduit via apressure tap extending through the fluid conduit.
 13. The system ofclaim 6, wherein the air flow sensor comprises a hot wire sensor, anorifice plate, a pitot tube, or a combination thereof.
 14. The system ofclaim 6, wherein the product comprises seed, granular fertilizer, or acombination thereof.
 15. The system of claim 6, wherein the fluidconduit is configured to convey the product from an air cart to theagricultural implement.
 16. A method for measuring product flow to anagricultural implement, comprising: measuring a pressure drop between anupstream portion of a fluid conduit and a downstream portion of thefluid conduit, wherein the fluid conduit is configured to convey productto the agricultural implement via an air flow in a downstream direction;measuring a flow rate of the air flow; measuring a velocity of the airflow; and determining a mass flow rate of the product based on thepressure drop, the flow rate of the air flow, and the velocity of theair flow.
 17. The method of claim 16, wherein measuring the pressuredrop comprises: measuring fluid pressure within the upstream portion ofthe fluid conduit; measuring fluid pressure within the downstreamportion of the fluid conduit; and determining the pressure drop based onthe measured fluid pressures.
 18. The method of claim 16, whereindetermining the mass flow rate of the product comprises determining themass flow rate of the product based on the pressure drop, the flow rateof the air flow, the velocity of the air flow, and at least oneempirical parameter associated with the product.
 19. The method of claim18, wherein the mass flow rate of the product is determined based on theequation:m _(p) =m _(a)·[(a ₁ e ^(a) ² ^(v))Δp−ln(b ₁ v ³ +b ₂ v ² +b ₃ v+b ₄)],where m_(p) is the mass flow rate of the product, m_(a) is a mass flowrate based on the flow rate of the air flow, Δp is the pressure drop, vis the velocity of the air flow, and a₁, a₂, b₁, b₂, b₃ and b₄ areempirical parameters.
 20. The method of claim 18, comprising selectingthe at least one empirical parameter from a list of empirical parametersbased on a selected product.